linux-kernel - Re: [PATCH v3 21/26] coresight: etm4x: Use TRCDEVARCH for component discovery

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Date:   Fri, 6 Nov 2020 14:42:28 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, mike.leach@...aro.org,
        coresight@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 21/26] coresight: etm4x: Use TRCDEVARCH for component
 discovery

On Wed, Oct 28, 2020 at 10:09:40PM +0000, Suzuki K Poulose wrote:
> We have been using TRCIDR1 for detecting the ETM version. This
> is in preparation for the future IP support.
> 
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
>  .../coresight/coresight-etm4x-core.c          | 46 +++++++++----------
>  1 file changed, 23 insertions(+), 23 deletions(-)

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

I'm out of time for today, I will resume on Monday.

Thanks,
Mathieu

> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 4ef47a2946a4..e36bc1c722c7 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -141,18 +141,6 @@ static void etm4_cs_unlock(struct etmv4_drvdata *drvdata,
>  		CS_UNLOCK(csa->base);
>  }
>  
> -static bool etm4_arch_supported(u8 arch)
> -{
> -	/* Mask out the minor version number */
> -	switch (arch & 0xf0) {
> -	case ETM_ARCH_V4:
> -		break;
> -	default:
> -		return false;
> -	}
> -	return true;
> -}
> -
>  static int etm4_cpu_id(struct coresight_device *csdev)
>  {
>  	struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> @@ -677,6 +665,26 @@ static const struct coresight_ops etm4_cs_ops = {
>  static bool etm_init_iomem_access(struct etmv4_drvdata *drvdata,
>  				  struct csdev_access *csa)
>  {
> +	u32 devarch = readl_relaxed(drvdata->base + TRCDEVARCH);
> +	u32 idr1 = readl_relaxed(drvdata->base + TRCIDR1);
> +
> +	/*
> +	 * All ETMs must implement TRCDEVARCH to indicate that
> +	 * the component is an ETMv4. To support any broken
> +	 * implementations we fall back to TRCIDR1 check, which
> +	 * is not really reliable.
> +	 */
> +	if ((devarch & ETM_DEVARCH_ID_MASK) == ETM_DEVARCH_ETMv4x_ARCH) {
> +		drvdata->arch = etm_devarch_to_arch(devarch);
> +	} else {
> +		pr_warn("CPU%d: ETM4x incompatible TRCDEVARCH: %x, falling back to TRCIDR1\n",
> +			smp_processor_id(), devarch);
> +
> +		if (ETM_TRCIDR1_ARCH_MAJOR(idr1) != ETM_TRCIDR1_ARCH_ETMv4)
> +			return false;
> +		drvdata->arch = etm_trcidr_to_arch(idr1);
> +	}
> +
>  	*csa = CSDEV_ACCESS_IOMEM(drvdata->base);
>  	return true;
>  }
> @@ -693,7 +701,6 @@ static bool etm_init_csdev_access(struct etmv4_drvdata *drvdata,
>  static void etm4_init_arch_data(void *info)
>  {
>  	u32 etmidr0;
> -	u32 etmidr1;
>  	u32 etmidr2;
>  	u32 etmidr3;
>  	u32 etmidr4;
> @@ -758,14 +765,6 @@ static void etm4_init_arch_data(void *info)
>  	/* TSSIZE, bits[28:24] Global timestamp size field */
>  	drvdata->ts_size = BMVAL(etmidr0, 24, 28);
>  
> -	/* base architecture of trace unit */
> -	etmidr1 = etm4x_relaxed_read32(csa, TRCIDR1);
> -	/*
> -	 * TRCARCHMIN, bits[7:4] architecture the minor version number
> -	 * TRCARCHMAJ, bits[11:8] architecture major versin number
> -	 */
> -	drvdata->arch = BMVAL(etmidr1, 4, 11);
> -
>  	/* maximum size of resources */
>  	etmidr2 = etm4x_relaxed_read32(csa, TRCIDR2);
>  	/* CIDSIZE, bits[9:5] Indicates the Context ID size */
> @@ -1602,7 +1601,7 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
>  				etm4_init_arch_data,  &init_arg, 1))
>  		dev_err(dev, "ETM arch init failed\n");
>  
> -	if (etm4_arch_supported(drvdata->arch) == false)
> +	if (!drvdata->arch)
>  		return -EINVAL;
>  
>  	etm4_init_trace_id(drvdata);
> @@ -1634,7 +1633,8 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
>  
>  	pm_runtime_put(&adev->dev);
>  	dev_info(&drvdata->csdev->dev, "CPU%d: ETM v%d.%d initialized\n",
> -		 drvdata->cpu, drvdata->arch >> 4, drvdata->arch & 0xf);
> +		 drvdata->cpu, ETM_ARCH_MAJOR_VERSION(drvdata->arch),
> +		 ETM_ARCH_MINOR_VERSION(drvdata->arch));
>  
>  	if (boot_enable) {
>  		coresight_enable(drvdata->csdev);
> -- 
> 2.24.1
>